After concrete is poured, it shrinks as it cures. Such shrinkage inherently causes cracking in the concrete at arbitrary locations and spacing. It is desirable to control the location of such cracking. For example, it is common to cut a slot in the upper surface of a partially cured roadway or sidewalk so as to force a crack beneath the cut. Sawing concrete is an extensive time and labor process. The cuts must be made at the proper time in the curing process, so as to avoid chipping of concrete around the soft cut, cracking at improper locations, and micro cracking around the saw cuts. The saw cuts must also be provided in the proper locations so as to avoid additional, undesirable cracking. Furthermore, saw cutting equipment, including the blades, are costly to buy and maintain. The cutting process also generates substantial dust which must be cleaned away, and which may raise health concerns with excessive inhalation of the dust. Operation of the saw cutting equipment also requires training so as to maintain safety. Saw cutting also causes loss of aggregate interlock at the top of the concrete pavement.
Various prior art devices have been inserted into the wet concrete for inducing cracks as the concrete cures, so that the location of the cracks can be controlled. However, it often is difficult to reach desired locations for such inserts, depending on the size of the concrete slab and location of the insert.
Also, unless sealed, water seeps into the cracks. In freezing conditions, it expands as it turns to ice, thereby breaking the concrete adjacent the cuts and cracks, thereby damaging the concrete surface. Sealing the cracks to preclude such freeze breakage of the concrete adds costs for material and labor. Also, sealing often must be periodically repeated due to shrinkage, drying and/or cracking of the sealing material.
Accordingly, a primary objective of the present invention is the provision of a device for inducing cracks at pre-selected locations in concrete and providing a drainage channel for water seeping into the cracks.
Another objective of the present invention is the provision of a device for inducing cracks in concrete and draining water from the cracks which is set on the concrete bed before the concrete is poured.
A further objective of the present invention is the provision of a concrete crack inducing and draining device which is simple to install.
Still another objective of the present invention is the provision of a concrete crack inducing and draining device which is effective in use.
Yet another objective of the present invention is the provision of a concrete crack inducing and draining device which supports concrete forms, such as 2×4's.
A further objective of the present invention is the provision of a concrete crack inducing and draining device which supports strengthening structures, such as dowels and re-bar.
Another objective of the present invention is the provision of a device for inducing cracks in concrete and providing drainage, wherein multiple devices can be assembled in parallel and/or perpendicular orientations.
Still another objective of the present invention is the provision of a device for inducing cracks in concrete and providing drainage which is economical to manufacture and durable in use.
These and other objectives will become apparent from the following description of the invention.